Effect of Chain-ends on the Mixed Polymer Brush Morphology

链端对混合聚合物刷形态的影响

• 批准号: 2003891
• 负责人: Padma Gopalan
• 金额: $ 45万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2003891&HistoricalAwards=false
• 关键词: Effect; Chain; ends; Mixed; Polymer

PART 1: NON-TECHNICAL SUMMARYPolymer brushes are long stringy molecules that are chemically anchored to a surface to form a dense, thin coating that alters the surface properties. While the chemical anchoring to the surface provides the required mechanical strength to the coating, the chemistry and structure of the polymer enables communication with the environment. Hence, these coatings have broad relevance in solving problems in materials science and in human health. They can act as sensors for rapid detection of biomarkers in biofluids when anchored to electronically active surfaces, direct cell growth for regenerative medicine, resist deposition of micro-organisms on surfaces, control flow of charge in batteries, control friction at relevant interfaces., etc. This research program will develop new synthetic methodologies to make these polymer brushes with well defined structure and chemistry. The methodology developed is high yielding, simple and reproducible on a wide range of surfaces, hence can be adapted by the coating industry. This program will develop characterization methods to aid in the molecular level understanding of the resulting structure. The research program will serve to inspire and involve undergraduate students in polymer science and engineering research, by working with graduate student mentors, through the REU program. Educational modules will also be developed for dissemination through UW-Madison’s institute for Chemical Education, a national center dedicated to STEM education through outreach and education research. PART 2: TECHNICAL SUMMARYThe research program will develop a highly versatile approach to grow mixed A/B polymer brushes from a substrate using a cross-linkable copolymer coating, which contains a polymerizable initiator (inimer) as a comonomer. Mixed A/B polymer brushes consist of chemically distinct A and B chains, randomly grafted to the surface. They show changing density, height and composition profile as a function of solvent environment. These polymer brushes will have high chain grafting density, uniform distribution of A and B graft points, controlled molecular weights, and excellent control over composition. Theory predicts the lowering of critical point for phase separation in mixed brushes compared to block copolymers, and the formation of nanoscale morphology. However, experimental studies have fallen short of validating these predictions. The gap between theory and experiments is attributable to lack of: a) experimental methods for uniform growth of high grafting density mixed brushes with controllable grafting ratios, and predictable chain lengths, (b) accounting for chain end-groups in theory and experiments, and (c) characterization methods to study the morphology. In this project the goal is to understand the role of chain-end density, size, distribution, and type on the A/B mixed brush morphology. This is a largely experimentally and theoretically unexplored area in polymer brushes. Key aspects of this research will be to develop synthetic strategies to append select chain end groups, quantification of the extent of functionalization and chain-end distribution by a combination of X-ray photoelectron spectroscopy and Resonant Soft X-ray scattering (RSoXS), and studying the effect of chain-end functionalization on lateral phase segregation by a combination of scattering and advanced microscopy techniques. The morphological insight developed through these experiments will contribute towards the broader understanding and application of polymer brushes..This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

第一部分： 非技术概述聚合物刷是化学锚定到表面上以形成改变表面性质的致密薄涂层的长的线状分子。虽然化学锚定到表面为涂层提供了所需的机械强度，但聚合物的化学和结构使其能够与环境连通。 因此，这些涂层在解决材料科学和人类健康问题方面具有广泛的相关性。当锚定到电子活性表面时，它们可以作为传感器用于快速检测生物流体中的生物标志物，指导再生医学的细胞生长，抵抗微生物在表面上的沉积，控制电池中的电荷流动，控制相关界面处的摩擦。该研究计划将开发新的合成方法，使这些聚合物刷具有明确的结构和化学性质。开发的方法是高产，简单和可重复的广泛的表面，因此可以适用于涂料行业。该计划将开发表征方法，以帮助在分子水平上理解所得结构。 该研究计划将通过REU计划与研究生导师合作，激励和参与高分子科学和工程研究的本科生。教育模块也将通过威斯康星大学麦迪逊分校的化学教育研究所，一个致力于通过推广和教育研究干教育的国家中心传播开发。第二部分： 技术概述该研究计划将开发一种高度通用的方法，使用交联共聚物涂层从基材生长混合A/B聚合物刷，该涂层含有可聚合引发剂（inimer）作为共聚单体。混合A/B聚合物刷由化学上不同的A和B链组成，随机接枝到表面。它们显示出作为溶剂环境的函数的变化的密度、高度和组成轮廓。这些聚合物刷将具有高的链接枝密度、A和B接枝点的均匀分布、受控的分子量和对组成的优异控制。 理论预测，相分离的临界点降低在混合刷相比，嵌段共聚物，和纳米形态的形成。然而，实验研究未能验证这些预测。理论与实验之间的差距可归因于缺乏：a）具有可控接枝率和可预测链长的高接枝密度混合刷均匀生长的实验方法，（B）理论和实验中考虑链末端基团，以及（c）研究形态的表征方法。 在这个项目中，目标是了解链端密度，大小，分布和类型的A/B混合刷形态的作用。这在聚合物刷中是一个很大程度上实验和理论上未探索的领域。本研究的关键方面将是开发合成策略，附加选择链端基，定量的功能化和链端分布的程度相结合的X射线光电子能谱和共振软X射线散射（RSoXS），并研究链端功能化的横向相分离的散射和先进的显微镜技术相结合的效果。通过这些实验开发的形态学洞察力将有助于更广泛地理解和应用聚合物刷。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估的支持。

项目成果

Formamide based monomer for highly functionalized polymers

• DOI: 10.1002/pol.20210651
• 发表时间: 2021-11
• 期刊: Journal of Polymer Science
• 影响因子: 3.4
• 作者: Ri Chen;Balamurugan Ayyakkalai;Jian Sun;Gene Lee;P. Gopalan

Chain End-Functionalized Dense Polymer Brushes from an Inimer Coating by SI-RAFT

• DOI: 10.1021/acs.langmuir.3c00733
• 发表时间: 2023-05-30
• 期刊: LANGMUIR
• 影响因子: 3.9
• 作者: Smith，Julia D.;Salas，Luis Adrian Padilla;Gopalan，Padma
• 通讯作者: Gopalan，Padma

Photoimageable Organic Coating Bearing Cyclic Dithiocarbonate for a Multifunctional Surface

• DOI: 10.1021/acsami.1c19559
• 发表时间: 2022-01-04
• 期刊: ACS APPLIED MATERIALS & INTERFACES
• 影响因子: 9.5
• 作者: An，Sol;Nam，Jieun;Kim，Myungwoong
• 通讯作者: Kim，Myungwoong

Synthesis of High Etch Contrast Poly(3-hydroxystyrene)-Based Triblock Copolymers and Self-Assembly of Sub-5 nm Features

• DOI: 10.1021/acs.macromol.1c01611
• 发表时间: 2021-10
• 期刊: Macromolecules
• 影响因子: 5.5
• 作者: Jian Sun;Changyeon Lee;C. Osuji;P. Gopalan

Selectively Grown Quantum Dot Active Region Lasers

选择性生长的量子点有源区域激光器

• DOI: 10.1109/jqe.2022.3145838
• 发表时间: 2022
• 期刊: IEEE journal of quantum electronics
• 影响因子: 2.5
• 作者: Mawst, L. J.;Kim, H.;Wei, W.;Talreja, D.;Kuech, T. F.;Gopalan, P.
• 通讯作者: Gopalan, P.